Ghrelin is a peptide hormone produced primarily by gastrointestinal cells. Receptors for ghrelin are highly expressed in regions of the hypothalamus that control feeding. Accordingly, ghrelin has been extensively studied for its ability to induce feeding behavior. However, ghrelin receptors are also expressed in other brain regions not traditionally associated with feeding behavior, such as the hippocampus. Ghrelin signaling is linked to obesity, diabetes and cardiovascular function. It has also been reported that increasing the levels of ghrelin leads to anti-depressant effects and that mice carrying a null mutation in the ghrelin receptor have increased depressive symptoms, suggesting that active ghrelin signaling has anti-depressant activity (13).